One of the objectives in elevator development work is to achieve efficient and economical utilization of building space. In recent years, this development work has produced various elevator solutions without machine room, among other things. Good examples of elevators without machine room are disclosed in specifications EP 0 631 967 (A1) and EP 0 631 968. The elevators described in these specifications are fairly efficient in respect of space utilization as they have made it possible to eliminate the space required by the elevator machine room in the building without a need to enlarge the elevator shaft. In the elevators disclosed in these specifications, the machine is compact at least in one direction, but in other directions it may have much larger dimensions than a conventional elevator machine.
In these basically good elevator solutions, the space required by the hoisting machine limits the freedom of choice in elevator lay-out solutions. Space is needed for the arrangements required for the passage of the hoisting ropes. It is difficult to reduce the space required by the elevator car itself on its track and likewise the space required by the counterweight, at least at a reasonable cost and without impairing elevator performance and operational quality. In a traction sheave elevator without machine room, mounting the hoisting machine in the elevator shaft is often difficult, especially in a solution with machine above, because the hoisting machine is a sizeable body of considerable weight. Especially in the case of larger loads, speeds and/or hoisting heights, the size and weight of the machine are a problem regarding installation, even so much so that the required machine size and weight have in practice limited the sphere of application of the concept of elevator without machine room or at least retarded the introduction of said concept in larger elevators. In modernization of elevators, the space available in the elevator shaft often limits the area of application of the concept of elevator without machine room. In many cases, especially when hydraulic elevators are modernized or replaced, it is not practical to apply the concept of roped elevator without machine room due to insufficient space in the shaft, especially in a case where the hydraulic elevator solution to be modernized/replaced has no counterweight. A disadvantage with elevators provided with a counterweight is the cost of the counterweight and the space it requires in the shaft. Drum elevators, which are nowadays rarely used, have the drawbacks of requiring heavy and complex hoisting machines with a high power consumption. Prior-art elevator solutions without counterweight are exotic, and no adequate solutions are known. Before, it has not been technically or economically reasonable to make elevators without a counterweight. One solution of this type is disclosed in specification WO9806655. A recent elevator solution without counterweight presents a viable solution. In prior-art elevator solutions without counterweight, the tensioning of the hoisting rope is implemented using a weight or spring, and this is not an attractive approach to implementing the tensioning of the hoisting rope. Another problem with elevator solutions without counterweight, when long ropes are used e.g. due to a large hoisting height or a large rope length required by high suspension ratios, is the compensation of the elongation of the ropes and the fact that, due to rope elongation, the friction between the traction sheave and the hoisting ropes is insufficient for the operation of the elevator.
Example embodiments of the present invention may develop the elevator without machine room so as to allow more effective space utilization in the building and elevator shaft. This means that the elevator may be installed in a fairly narrow elevator shaft if necessary. Other example embodiment of the present invention may achieve an elevator in which the hoisting rope has a good grip/contact on the traction sheave. Other example embodiment of the present invention may achieve an elevator solution without counterweight and compromising the properties of the elevator. Other example embodiment of the present invention may eliminate rope elongation.
Accordingly, example embodiments may be achieved without compromising the possibility of varying the basic elevator lay-out.
The elevator of the invention is characterized by what is disclosed in the characterization part of claim 1. The method of the invention is characterized by what is disclosed in the characterization part of claim 10. The use according to the invention is characterized by what is disclosed in claim 11. Other embodiments of the invention are characterized by what is disclosed in the other claims. Some inventive embodiments are also discussed in the description section of the present application. The inventive content of the application can also be defined differently than in the claims presented below. The inventive content may also consist of several separate inventions, especially if the invention is considered in the light of expressions or implicit sub-tasks or from the point of view of advantages or categories of advantages achieved. In this case, some of the attributes contained in the claims below may be superfluous from the point view of separate inventive concepts.
Example embodiments of the present invention may provide one or more of the following advantages, among others:                Using a small traction sheave, a very compact elevator and/or elevator machine is achieved        A good traction sheave grip, which is achieved in particular by using Double Wrap roping, and lightweight components allow the weight of the elevator car to be considerably reduced        A compact machine size and thin, substantially round ropes permit the elevator machine to be relatively freely placed in the shaft. Thus, the elevator solution of the invention can be implemented in a fairly wide variety of ways in the case of both elevators with machine above and elevators with machine below.        The elevator machine can be advantageously placed between the car and a shaft wall.        All or at least part of the weight of the elevator car can be carried by the elevator guide rails        Applying the invention allows effective utilization of the cross-sectional area of the elevator shaft        The light and thin ropes are easy to handle, allowing considerably easier and faster installation        E.g. in elevators for a nominal load below 1000 kg, the thin and strong steel wire ropes preferably used in the invention have a diameter of the order of only 3–5 mm, although even thinner and thicker ropes can be used        With rope diameters of about 6 mm or 8 mm, fairly large and fast elevators according to the invention can be achieved        It is possible to use either coated or uncoated ropes        The use of a small traction sheave makes it possible to use a smaller elevator drive motor, which means reduced drive motor acquisition/manufacturing costs        The invention can be applied in gearless and geared elevator motor solutions        Although the invention is primarily intended for use in elevators without machine room, it can also be applied in elevators with machine room.        In the invention a better grip and a better contact between the hoisting ropes and the traction sheave are achieved by increasing the contact angle between them.        Due to the improved grip, the size and weight of the car can be reduced.        The space saving potential of the elevator of the invention is increased as the space required by the counterweight can be at least partially eliminated        As a result of a lighter and smaller elevator system, energy savings and therefore cost savings are achieved        The placement of the machine in the shaft can be relatively freely chosen as the space required by the counterweight and counterweight guide rails can be used for other purposes        By mounting at least the elevator hoisting machine, the traction sheave and a rope sheave functioning as a diverting pulley in a complete unit which is fitted as a part of the elevator of the invention, considerable savings in installation time and costs will be achieved.        In the elevator solution of the invention, it is possible to dispose all ropes in the shaft on one side of the elevator car; for example, in the case of rucksack type solutions, the ropes can be arranged to run behind the elevator car in the space between the elevator car and the back wall of the elevator shaft,        The invention makes it easy to implement scenic-type elevator solutions as well        Since the elevator solution of the invention does not necessarily comprise a counterweight, it is possible to implement elevator solutions in which the elevator car has doors in several walls, in an extreme case even in all the walls of the elevator car. In this case, the guide rails of the elevator car are disposed at the corners of the elevator car.        The elevator solution of the invention can be implemented with several different machine solutions        The suspension of the car can be implemented using almost any suitable suspension ratio        Compensation of rope elongations by means of a compensating system according to the invention is a cheap and simple structure to implement        Compensation of rope elongations by means of a lever is a cheap and light structure        Using the rope elongation compensation solutions of the invention, it is possible to achieve a constant ratio between the forces T1/T2 acting on the traction sheave        The ratio between the forces T1/T2 acting on the traction sheave is independent of the load        By using the rope elongation compensating system of the invention, unnecessary stress on the machine and ropes can be avoided        By using the rope elongation compensating solutions of the invention, the relation between the forces T1/T2 can be optimized to achieve a desired value        The solutions of the invention for compensating rope elongation are safe solutions which make it possible to guarantee the required friction/contact between the traction sheave and the hoisting rope in all situations        In addition, the rope elongation compensating solutions of the invention make it unnecessary to stress the hoisting ropes in order to ensure friction between the traction sheave and the hoisting rope by loads larger than necessary, and consequently the useful life of the hoisting ropes is increased and their damage susceptibility is reduced        When rope elongation is compensated using the arrangement of the invention for compensating rope elongation with compensating sheaves of different diameters, it will be possible using this solution to compensate even very large rope elongations, depending on the diameters of the pulleys used        By using a rope elongation compensating solution according to the invention in which the compensating apparatus used is a differential gear, it is possible to compensate even large rope elongations, especially in the case of high hoisting heights.        
The primary area of application of the invention is elevators designed for the transportation of people and/or freight. A typical area of application of the invention is in elevators whose speed range is about 1.0 m/s or below but may also be higher. For example, an elevator having a traveling speed of 0.6 m/s is easy to implement according to the invention.
In both passenger and freight elevators, many of the advantages achieved through the invention are pronouncedly brought out even in elevators for only 2–4 people, and distinctly already in elevators for 6–8 people (500–630 kg).
In the elevator of the invention, normal elevator hoisting ropes, such as generally used steel ropes, are applicable. In the elevator, it is possible to use ropes made of artificial materials and ropes in which the load-bearing part is made of artificial fiber, such as e.g. so-called “aramid ropes”, which have recently been proposed for use in elevators. Applicable solutions also include steel-reinforced flat ropes, especially because they allow a small deflection radius. Particularly well applicable in the elevator of the invention are elevator hoisting ropes twisted e.g. from round and strong wires. From round wires, the rope can be twisted in many ways using wires of different or equal thickness. In ropes well applicable in the invention, the wire thickness is below 0.4 mm on an average. Well applicable ropes made from strong wires are those in which the average wire thickness is below 0.3 mm or even below 0.2 mm. For instance, thin-wired and strong 4 mm ropes can be twisted relatively economically from wires such that the mean wire thickness in the finished rope is in the range of 0.15–0.25 mm, while the thinnest wires may have a thickness as small as only about 0.1 mm. Thin rope wires can easily be made very strong. In the invention, rope wires having a strength greater than 2000 N/mm2 can be used. A suitable range of rope wire strength is 2300–2700 N/mm2. In principle, it is possible to use rope wires having a strength of up to about 3000 N/mm2 or even more.
The elevator of the invention, in which the elevator car is suspended by means of hoisting ropes consisting of a single rope or several parallel ropes, said elevator having a traction sheave which moves the elevator car by means of the hoisting ropes, has rope portions of the hoisting ropes going upwards and downwards from the elevator car, and the rope portions going upwards from the elevator car are under a first rope tension (T1) which is greater than a second rope tension (T2), which is the rope tension of the rope portions going downwards from the elevator car. In addition, the elevator comprises a compensating system for keeping the ratio (T1/T2) between the first rope tension and the second rope tension substantially constant.
In the method of the invention for forming an elevator, the elevator car is connected to elevator roping hoisting the elevator car, said roping consisting of a single rope or a plurality of parallel ropes and comprising rope portions going upwards and downwards from the elevator car, and that the elevator roping is provided with a compensating system for keeping the ratio (T1/T2) between the rope forces acting in upward and downward directions substantially constant.
By increasing the contact angle by means of a rope sheave functioning as a diverting pulley, the grip between the traction sheave and the hoisting ropes can be increased. In this way, the car can be made lighter and its size can be reduced, thus increasing the space saving potential of the elevator. A contact angle of over 180° between the traction sheave and the hoisting rope is achieved by using one or more diverting pulleys. The need to compensate the rope elongation arises from the friction requirements, to ensure that a grip sufficient for operation and safety of the elevator exists between the hoisting rope and the traction sheave. On the other hand, it is essential in respect of elevator operation and safety that the rope portion below the elevator car in an elevator solution without counterweight should be kept sufficiently tight. This can not necessarily be achieved using a spring or a simple lever.